Field of The Invention
The invention is directed to a method and to a circuit arrangement for controlling the transmission of message blocks within a transmission system.
EP-A1-0 475 180, corresponding to U.S. Pat. No. 5,243,594 incorporated herein by reference, has already disclosed a telecommunication switching system for the transmission of message blocks wherein line termination equipment units connected to transmission lines are connected via an internal line system to a plurality of switching computers, and one of the switching computers as well as at least one of the line termination equipment units are involved in the transmission of message blocks during the course of a call. Among other things, it is thereby provided that message blocks previously inserted into a transmission queue proceeding from a switching computer are first continuously transmitted to a line termination equipment unit coming into consideration for the respective call, i.e. with an open window size W=.infin., and are inserted into a reception queue thereat. When a predetermined filling degree of such a reception queue has been reached, the transmission of message blocks to the respective line termination equipment unit is interrupted for a defined time span. The message blocks that are thereby initially not capable of transmission are thereby inserted into a recovery or reset queue individually established for the respective line termination equipment unit. After the expiration of the defined time span, the transmission of message blocks to the respective line termination equipment unit is then reassumed, initially taking the message blocks inserted into the previously established recovery or reset queue into consideration.
Alternatively or additionally thereto, line queues individually allocated to the transmission lines connected to a line termination equipment unit can be provided in a line termination equipment unit. The message blocks initially output by a switching computer with an open window size (W=.infin.) are inserted into these line queues. When a defined, first filling degree of such a line queue is upwardly exceeded, a corresponding control signal is transmitted proceeding from the respective line termination equipment unit to the switching computer coming into consideration. In response thereto, the message blocks intended for the corresponding line queue are only transmitted to the respective line termination equipment unit with a window size of W=1. When a defined, second filling degree lying above the first filling degree is reached for a line queue, this again being indicated by a corresponding control signal proceeding from the respective line termination equipment unit, by contrast the transmission of message blocks to be inserted into the corresponding line queue is interrupted, proceeding from the respective switching computer. The message blocks that are initially incapable of transmission as a result thereof are thereby inserted into a recovery or reset queue allocated to the corresponding line queue. Only after the expiration of a defined time span is the transmission of message blocks that are to be inserted into the corresponding line queue reassumed proceeding from the respective switching computer, namely initially taking the message blocks inserted into the recovery or reset queue into consideration.
The afore-mentioned control techniques for the transmission of message blocks between switching computers and line termination equipment units thus represent a control or monitoring system. In particular, the size of the afore-mentioned line queues is thereby dependent on the overall running time of the control loop. The control loop is thereby composed of the transmission of a message block, of the recognition of an overload in one of the line queues, the return transmission of a corresponding control signal and of the reaction of the switching computer to such a control signal. Relatively long running times and memory sizes can potentially result therefrom, these being mainly undesirable.